Conventionally, as means for grasping a tendency of data in a data series including three or more variables, systems for displaying a graph in a three-dimensional coordinate space have been proposed.
For example, Patent Literature 1 describes a display control device that rotates and displays a graph having a data series set in a three-dimensional coordinate space (hereinafter, the graph is referred to as three-dimensional graph) in accordance with a rotation operation. When the three-dimensional graph is rotated in an arbitrary direction in accordance with the rotation operation, a user can easily grasp an outline of the three-dimensional graph and the like.
Further, when label information such as a unit of data, a numerical value of a scale, or a name of a data series is displayed on axes (X, Y, Z) of a three-dimensional graph, the user can read values or meaning of the data in the three-dimensional graph while comparing the data with the axes.
As a method for displaying the label information, there is a method for displaying characters of the label information in a character style as viewed from the front without distortion on a constant basis, regardless of a display angle of the three-dimensional graph as viewed from the screen (hereinafter, the characters in a character style is described as front style).
However, in the above display method, even if the three-dimensional graph is rotated, the label information is not rotated to display the characters of the label information in the front style. Therefore, there is a problem that the user has a difficulty in distinguishing which part of the three-dimensional graph the label information is attached to or in grasping the sense of depth of the three-dimensional coordinate space.
Meanwhile, a window display device described in Patent Literature 2 performs, when rotating and displaying a window in a virtual space, perspective projection processing for a character string of the window in accordance with the rotation to provide a spatial depth. By application of this technology to display of label information of a three-dimensional graph, the sense of depth in the three-dimensional coordinate space is improved and the user can easily grasp the outline of the three-dimensional graph and an axis to which the label information is attached.